Neuropeptide Y (hereinafter referred to as NPY) is a peptide which consists of 36 amino acid residues and was isolated from porcine brain in 1982. NPY is widely distributed in the central nervous system and peripheral tissues of humans and animals.
It has been reported that NPY possesses a stimulatory action on food intake, an anti-seizure activity, a learning-enhancing action, an anti-anxiety activity, an anti-stress activity, etc. in the central nervous system, and it may be pivotally involved in central nervous system diseases such as depression, Alzheimer's disease and Parkinson's disease. NPY is thought to be involved in cardiovascular diseases, since it induces a contraction of smooth muscles such as blood vessels or cardiac muscles in peripheral tissues. Furthermore, NPY is also known to be involved in metabolic diseases such as obesity, diabetes and hormone abnormalities (Non-patent Document 1). Therefore, a pharmaceutical composition having NPY Y5 receptor antagonistic activity is expected as medicine for preventing or treating the above-mentioned various diseases associated with the NPY receptor.
Six subtypes of NPY receptors have now been identified: Y1, Y2, Y3, Y4, Y5 and Y6 (Non-patent Document 2). It has been suggested that the Y5 receptor is at least involved in the feeding behavior and its antagonist is expected as an anti-obesity drug (Non-patent Documents 3 to 5).
Benzimidazole and imidazopyridine derivatives having sulfonyl group and having NPY Y5 receptor antagonistic activity are disclosed in Patent Document 1. Amine derivatives having sulfonyl group and having NPY Y5 receptor antagonistic activity are disclosed in Patent Document 2 and the like. Amide derivatives having sulfonyl group and having NPY Y5 receptor antagonistic activity are disclosed in Patent Documents 3 to 5 and the like. The structures of these compounds are different from those of the compounds of this invention.
Compounds having different structures from the compounds of this invention and having NPY Y5 receptor antagonistic activity are disclosed in Patent Document 6 and the like.
Furthermore, although compounds having similar structures to compounds of this invention are disclosed in Patent Documents 7 to 14, the activities of their compounds are quite different from those of the compounds of this invention and these documents do not suggest this invention.